Note 1 - Basis of Presentation and Significant Accounting Policies - Option Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2022
Options, Outstanding Balance (in shares)	2,095,538
Weighted Average Exercise Price, Outstanding Balance (in dollars per share)	$ 3.74
Weighted Average Remaining Contractual Period in Years, Outstanding Ending Balance (Year)	7 years 7 months 28 days	7 years 3 months 14 days
Options, Granted (in shares)	579,350
Weighted Average Exercise Price, Granted (in dollars per share)	$ 0.84
Weighted Average Remaining Contractual Period in Years, Granted (Year)	9 years 9 months 18 days
Options, Exercised (in shares)	(2,550)
Weighted Average Exercise Price, Exercised (in dollars per share)	$ 0.66
Weighted Average Remaining Contractual Period in Years, Exercised (Year)	6 years
Options, Forfeited and cancelled (in shares)	(159,211)
Weighted Average Exercise Price,Forfeited and cancelled (in dollars per share)	$ 5.16
Options, Outstanding at end of year (in shares)	2,513,127	2,095,538
Weighted Average Exercise Price, Outstanding Balance (in dollars per share)	$ 2.98	$ 3.74
Options, Exercisable at end of year (in shares)	1,500,786
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 3.55
Weighted Average Remaining Contractual Period in Years, Exercisable Ending Balance (Year)	6 years 8 months 19 days